Add :indeterminate pseudo class support for radio button input

Source/core/html/HTMLInputElement.cpp

Index: Source/core/html/HTMLInputElement.cpp
diff --git a/Source/core/html/HTMLInputElement.cpp b/Source/core/html/HTMLInputElement.cpp
index 233384b9aad6835862fb4ed61aec4d26020f65d2..95af2adf36878e885200047594c61c1c25847e8f 100644
--- a/Source/core/html/HTMLInputElement.cpp
+++ b/Source/core/html/HTMLInputElement.cpp
@@ -1701,7 +1701,7 @@ String HTMLInputElement::defaultToolTip() const
 
 bool HTMLInputElement::shouldAppearIndeterminate() const
 {
-    return m_inputType->supportsIndeterminateAppearance() && indeterminate();
+    return m_inputType->shouldAppearIndeterminate();
 }
 
 bool HTMLInputElement::isInRequiredRadioButtonGroup()
@@ -1712,8 +1712,10 @@ bool HTMLInputElement::isInRequiredRadioButtonGroup()
     return false;
 }
 
-HTMLInputElement* HTMLInputElement::checkedRadioButtonForGroup() const
+HTMLInputElement* HTMLInputElement::checkedRadioButtonForGroup()
 {
+    if (checked())
+        return this;

[tkent, 2014/07/15 01:31:50]

This changes a behavior.  For example,
- the input type is not radio
- this input is not in a Document tree.

Is it ok?

[keishi, 2014/07/15 03:05:30]

I think this is correct and the current behavior is a bug.

This test gives true on Chrome but false on Firefox.
http://jsbin.com/lokocepo/2/edit

Single radio buttons should form its own radio button group so I think the
correct output is false.
https://www.w3.org/Bugs/Public/show_bug.cgi?id=21820

     if (RadioButtonGroupScope* scope = radioButtonGroupScope())
         return scope->checkedButtonForGroup(name());
     return 0;